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TT: Tiefe Temperaturen

TT 25: Postersitzung III: Pinning und Vortexdynamik, Massive HTSL, Bandleiter, Transporteigenschaften in HTSL, SL dünner Filme, Elektronen und Phononen in HTSL, Tunneln, Borkarbide, Quantenphasen und Metall-Isolator-Überg
änge, Anwendungen, Sonstiges

TT 25.15: Poster

Donnerstag, 29. März 2001, 14:30–17:00, Rang S\ 3

Charge Imbalance Effects in Nonlocal Measurements on YBa₂Cu₃O₇ Thin Films — •S. Manzoor¹, F. Mrowka¹, P. Esquinazi¹, M. Lorenz¹, and K. Zimmer² — ¹Abt. Supraleitung und Magnetismus, Institut für Experimentelle Physik II, Universität Leipzig, D-04103 Leipzig — ²Institut für Oberflächenmodifizierung, Permoserstr. 15, D-04303 Leipzig

We report on nonlocal measurements of in plane voltages on Y123 thin films in transverse applied magnetic fields up to 9 Tesla. We find anomalously large nonlocal voltages at T ≤ T_c. The nonlocal signal is found to decay on a length scale X_c^nl much larger than that of the parasitic signal proportional to the local voltage X_c^l. At T > T_c(H) X_c^nl is approximately independent of field, while at lower temperatures it displays a significant field dependence, tending towards saturation at higher fields µ₀ H > 2  T. We attribute our results to the existence of long lived quasiparticles at the nodes of d-wave superconductors and the resulting charge imbalance.